下颌角骨折坚强内固定的生物力学分析

目的 比较下颌角骨折后两种不同的内固定方法对其应力分布的影响。方法 采用成人干燥无牙下颌骨,建立由咬肌、颞肌、翼内肌和翼外肌4组肌肉共同加载,由硅橡胶模拟颞下颌关节结构功能状态下的下颌骨机械力学模型。采用电阻应变片的测量方法,分析不同坚强内固定方式,即仅在下颌角上缘张力带固定一个小型接骨板和在下颌角下缘附加固定一个小型接骨板对下颌骨应力分布的影响。结果 两种固定方法下健侧的应力分布与骨折前均无显著性差异（P＞0.05）,但是仅在下颌角上缘固定一个小型接骨板将使患侧下颌骨下缘呈张应力趋势,造成应力轨迹的中断。结论 两种固定方法均可以恢复健侧的应力轨迹,但是要获得骨折区域充分的稳定性,固定两个小型接骨板是必要的     

下颌角骨折张力带固定与下颌骨下缘固定的临床对比研究

目的　探讨下颌角骨折小型接骨板张力带固定的临床可行性。方法　研究组 2 7例 2 8侧下颌角骨折行小型接骨板张力带固定 ,对照组 19例行下颌骨下缘固定 ,两组的不利型骨折比例分别为 82 %和 95 % ,严重移位骨折比例 2 5 %和 85 % ,术前感染比例 0和 2 5 % ,骨折复位同期拔牙比例5 5 %和 33% ,病例复查率 89%和 79% ,平均复查期 36周和 31周 ,经临床及X线检查进行比较分析。结果　研究组和对照组的术后感染率分别为 10 71%和 5 0 0 % ,干扰率 7 40 %和 5 2 6 % ,张口受限率 14 81%和 10 5 3% ,创伤性关节炎发生率 11 11%和 2 1 0 5 %。张力带固定组 2 1 43%的骨折术后出现下颌骨下缘分离或再移位 ,同时伴外骨痂形成 ;下颌下缘固定组 10 %的骨折存在复位固定缺陷 ,分别发生在未设张力带的加压固定和两个小型接骨板并行固定。结论　下颌角骨折采用小型接骨板张力带固定的稳定性不足 ,只适用于有利型和轻度移位的骨折 ,不利型和严重移位的骨折应增加下缘固定。稳定性不足和复位同期拔牙是术后感染的可能原因。     

A computer study of biodegradable plates for internal fixation of mandibular angle fractures.

PURPOSE: This computer-based study was performed to determine the suitability of small biodegradable plate systems for mandibular angle fractures. MATERIALS AND METHODS: In a 3-dimensional computer model of the mandible, fracture mobility and plate strain were calculated for bite forces applied on 13 bite points on the dental arch. The angle fracture was fixed with 2 polylactide (PLA) midiplates or with 2 PLA maxiplates. The first plate was positioned buccally on the external oblique ridge. Two positions of the second plate were studied: halfway up the height of the mandible or on the lower border. Maximum fracture mobility was set at a limit of 150 microm to enable undisturbed fracture healing. Maximum plate strain was set at the yield strain of PLA. RESULTS: Fixation with the PLA maxiplates, with the second plate positioned halfway up the height of the mandible, resulted in fracture mobility below the set limit for all bite points. For the other PLA fixation strategies, fracture mobility exceeded the set limit. Fixation with the second plate positioned halfway up the height of the mandible generally resulted in less fracture mobility than with the plate positioned on the lower border. The yield strain of PLA was not exceeded in any of the fixation strategies. CONCLUSIONS: Based on the computer model, 2 PLA maxiplates are suitable for fixation of mandibular angle fractures. One plate should be positioned buccally on the external oblique ridge, and the other should be positioned halfway up the height of the mandible.     

Outcomes of patients with teeth in the line of mandibular angle fractures treated with stable internal fixation.

PURPOSE: This study examines the relationship between postoperative infection and/or need for plate removal with the presence and management of teeth in the line of mandibular angle fractures. METHODS: Data were collected on patients treated by intraoral open reduction and internal fixation for fractures of the mandibular angle during an 8-year period. Outcome variables were postoperative infection and need for removal of the bone plate(s). The relationships of demographic variables, teeth in the line of fracture, and management of teeth in the line of fracture were analyzed using standard statistical methods. RESULTS: Four hundred two patients had sufficient follow-up for inclusion in the study. A tooth was present in the fracture line 85% of the time. Teeth in the fracture were removed in 75% of the fractures that contained teeth. Postoperative complications occurred in 19% of the sample. Fractures not containing teeth at the time of fracture had a 15.8% rate of postoperative infection compared with 19.1% for patients who had teeth in the fracture (P = NS). For angle fractures associated with a tooth, when the tooth was retained, the incidence of infection was 19.5%. When the tooth was removed, the incidence was 19.0% (P = NS). CONCLUSIONS: There is an increased risk for postoperative complications when a tooth is present, but the increase is not statistically significant. The incidence of postoperative infection and/or the need for plate removal is not affected by whether the tooth in the fracture is removed.     

Biomechanical comparison of a new technique of mandibular angle fractures: biplanar and bicortical superior proximal 3 holes and bicortical inferior plate fixation

Miniplates have been used for mandibular angle fractures during the past 2 decades. The technique of placing single miniplate at the upper border based on the tension lines of the fracture was proposed by Michelet and Champy. The need for a second miniplate to be applied to the lower mandible has been discussed recently. Biomechanical comparison of biplanar and monoplanar dual-miniplate fixation techniques was investigated by Haug. Our hypothesis is in dual-miniplate fixation; the proximal 3 holes of superior border miniplate could be fixated by bicortical screws. The first 2 are at the proximal bone segment and are not related to the tooth and also superior to the alveolar nerve. Generally, the third molar tooth is extracted because it is at the fracture site. Hence, the proximal third hole could also be fixated by bicortical screws. We define a biplanar dual-miniplate technique in which the lower plate and the proximal 3 holes of the upper plate are fixated by bicortical screws. We have designed a study for biomechanical comparison of our method and popular types of mandibular fixation methods.     

Superior border plating technique in the management of isolated mandibular angle fractures: a retrospective study of 50 consecutive patients.

PURPOSE: To determine the complication rate for patients presenting with isolated mandibular angle fractures treated by open reduction and internal fixation using a single superior border miniplate technique. PATIENTS AND METHODS: This is a retrospective study of consecutive patients with isolated mandibular angle fractures treated using a specific protocol at a Regional Oral and Maxillofacial Department between January 1998 and December 2004. Patient demographics, fracture etiology, length of hospital stay, removal of third molar, and postoperative complications were recorded. Preoperative and postoperative inferior alveolar nerve function was recorded. Objective sensory testing and patient interviews were conducted to determine the incidence of postoperative sensory deficit. RESULTS: The study population included 50 patients presenting with isolated mandibular angle fractures, 6 patients (12%) experienced complications requiring bone plate removal. These complications were minor and occurred after fracture healing as follows: 4 patients (8%) experienced superficial soft tissue infection associated with the bone plate, treated with oral antibiotics, 1 patient (2%) experienced bone plate exposure, and a further patient (2%) presented with a fractured bone plate. All 6 patients (12%) were treated by bone plate removal under general anesthesia as elective day case surgery. Thirty-nine (78%) patients had long-term sensory follow-up, mean 37 months (2 to 84 months). Permanent inferior alveolar sensory deficit (>12 months) was present in 4 (8%). Five of 26 (19%) patients with normal postinjury/preoperative sensory function had a postoperative sensory deficit. All patients in this group reported recovery of normal sensation within 6 months. CONCLUSIONS: The results of this study suggest that the complication rates associated with the treatment of isolated mandibular angle fractures using a superior border plating technique, in this patient population, is relatively low (12%). The complications were all minor in nature. There was a permanent (>12 months) inferior alveolar sensory deficit in 4 (8%) patients.     

不同程度老年人萎缩性无牙颌下颌骨骨折的内固定方式选择及相关生物力学分析

目的:比较3种不同程度萎缩性无牙颌下颌骨骨折的不同内固定方式及其效果。方法:构建不同程度的萎缩性无牙颌下颌骨体部骨折治疗模型,进行三维有限元分析,比较相同应力条件下骨折段位移的改变以及钛板的应力分布情况。结果:下颌骨Ⅲ度萎缩,采用1块2.0 mm 4孔钛板在下颌骨上缘进行固定,其骨折处移位较其余6种工况明显增大;相同萎缩程度的下颌骨,采用重建板固定比采用其他内固定方式骨折断端位移明显减少。Ⅲ度萎缩的下颌骨采用小型钛板固定,钛板所受应力分别接近及超过钛板的屈服极限。结论:对于Ⅰ度萎缩的无牙颌下颌骨骨折病例,下颌骨外侧双板固定以及下颌骨下缘重建板固定均能取得较为满意的固定稳定性,对于Ⅱ及Ⅲ度萎缩的无牙颌下颌骨骨折病例,下颌骨下缘重建板固定可以获得更好的固位稳定性。     

Treatment modalities for mandibular angle fractures.

PURPOSE: Management of mandibular angle fractures is often challenging and results in the highest complication rate among fractures of the mandible. Optimal treatment for angle fractures remains controversial. Historically, treatment of mandible fractures included intraoperative maxillomandibular fixation (MMF) along with rigid internal fixation. More recently, noncompression plates miniplates, which produce only relative stability, have gained popularity. The absolute necessity of intraoperative MMF as an adjunct to internal fixation has also become controversial. The current trends in the management of simple, noncomminuted mandibular angle fractures are examined. MATERIALS AND METHODS: A survey was submitted to North American and European AO ASIF (Arbeits-gemeinschaft fur Osteosynthesefragen Association for the Study of Internal Fixation) faculty in July 2001. Statistical analysis of results included both Fisher's exact and chi-square tests. Results were considered significant if P <.05. RESULTS: One hundred ten of 127 potential responses were received (87%). Among 104 surgeons who treat mandible fractures, 86 (83%) treat more than 10 mandibular fractures per year. Preferred techniques for simple, noncomminuted mandibular angle fractures in this group were: single miniplate on the superior border (Champy technique) with or without arch bars (44 surgeons, 51%); tension band plate on the superior border and nonlocking, bicortical screw plate on the inferior border (11 surgeons, 13%); dual miniplates (9 surgeons, 10%); a locking screw plate on the inferior border only (6 surgeons, 7%), and 3-dimensional plates (5 surgeons, 6%). Eleven surgeons (13%) gave multiple answers. Although only 13% of surgeons surveyed primarily use the combination of tension band and nonlocking, bicortical screw plates, many surgeons (73%) continue to use this technique in certain circumstances. Within this group, 32 (51%) place screws in a neutral position, while 31 (49%) place screws in an eccentric position, resulting in compression. For simple noncomminuted angle fractures, the number of surgeons performing internal fixation without MMF were: 14 often (16%); 20 occasionally (23%); 17 seldom (20%); and 35 never (41%). Surgeons treating more than 10 versus those who treat less than 10 fractures per year, International versus North American faculty, and Oral and Maxillofacial surgeons (OMS) versus non-OMS surgeons were compared. Surgeons who treat more than 10 fractures per year favor the Champy technique over the tension band and bicortical plate combination (44 [51%] vs 11 [13%]), while those surgeons who treat less than 10 per year favor the tension band and bicortical plate combination over the Champy technique (9 [50%] vs 3 [17%]; P < .01, Fisher exact test). International faculty are less likely to use intraoperative MMF than North American faculty (29 [81%] vs 31 [43%]; P < .01, Fisher exact test). OMS surgeons are less likely to use the tension band and bicortical plate combination than non-OMS surgeons (22 [56%] vs 42 [90%]; P < .017, Fisher exact test). CONCLUSION: This survey suggests an evolution in the management of mandibular angle fractures. A single miniplate plate on the superior border of the mandible has become the preferred method of treatment among AO faculty. When using large, inferiorly based plates more surgeons are now favoring neutral rather than eccentric screw placement. Intraoperative MMF is not considered mandatory by some surgeons in certain circumstances.     

下颌角骨折张力线内固定治疗方法的改进及其效果分析

目的改进口内切开复位治疗下颌角骨折的方法并对其临床效果进行比较探讨。方法下颌角骨折112例患者(115侧),分为A、B、C三组,均使用张力带内固定,B组、C两组分别加用口内切口下颌角外侧面行补偿固定和术后颌间固定,术后随访半年,对术后感染、咬合关系紊乱、体重丧失、颞颌关节异常和张口受限等方面进行综合比较。结果单纯张力带内固定组术后感染率为13.1%,有2例咬合关系紊乱,并有39.4%的病例下颌角下缘出现明显的外骨痂;其它两组感染率为5%、2.9%,咬合关系良好,加用颌间固定的C组体重丧失率和张口受限率为8.74%和47.1%,高于其它两组。结论单纯张力线内固定可治疗下颌角骨折,但存在着较大的局限性,口内切开复位下颌角外侧面补偿固定和术后颌间固定作为两种辅助治疗方法,在避免口外切口的同时,大大增加了治疗效果和适应证。     

下颌角骨折治疗后并发症的临床分析

目的研究下颌角骨折治疗后并发症,分析原因并提出预防方法。方法回顾分析我院206例下颌角骨折患者的治疗及并发症情况,分颌间固定组62例,内固定组120例,颅颌绷带组24例。结果治疗后发生的并发症有骨感染4例,医源性损伤2例,牙合干扰3例,错牙合畸形2例,颞下颌关节功能紊乱病2例。结论下颌角骨折的治疗应首选坚强内固定,应选择正确的手术方案,加强术前、术后抗感染治疗及术后肌功能训练,对骨折线上的阻生齿应尽可能保留,以减少并发症。     

Use of straight and curved 3-dimensional titanium miniplates for fracture fixation at the mandibular angle.

PURPOSE: The aim of this follow-up study was to evaluate the clinical usefulness of a new type of 3-dimensional (3D) miniplate for open reduction and monocortical fixation of mandibular angle fractures. PATIENTS AND METHODS: In 20 consecutive patients, noncomminuted mandibular angle fractures were treated with open reduction and fixation using a 2 mm 3D miniplate system in a transoral approach. All patients were systematically monitored until 6 months postoperatively. Among the outcome parameters recorded were infection, hardware failure, wound dehiscence, and sensory disturbance of the inferior alveolar nerve. RESULTS: The mean operation time from incision to wound closure was 65 minutes. Two patients had a mucosal wound dehiscence with no consequences. None developed an infection requiring a plate removal. All but 2 patients had normal sensory function 3 months after surgery. Plate fracture occurred in one patient in whom a preceding surgical removal of the third molar had been the reason for the mandibular fracture. In the absence of clinical symptoms, the patient declined plate removal. On final follow-up, fracture healing was considered clinically complete in all patients. CONCLUSIONS: The 3D plating system described here is suitable for fixation of simple mandibular angle fractures and is an easy-to-use alternative to conventional miniplates. The system may be contraindicated in patients in whom insufficient interfragmentary bone contact causes minor stability of the fracture.     

Treatment of condyle fracture caused by mandibular angle ostectomy

A prominent mandibular angle is considered to be unattractive in Asian countries because it gives the face a square and muscular appearance. Successful correction by angle ostectomy has been reported, but one of the serious complications of angle reduction ostectomy is fracture of the mandibular condyle. If the ostectomy line is misdirected vertically, the condyle may be fractured. The authors experienced two cases of condylar fracture during angle reduction. Case 1 was a pulled-out condylar fracture, where an L-shaped miniplate was then attached by external approach, and intermaxillary fixation (IMF) with arch bar was used on postoperative day 14. With release of the IMF, a systematic approach for a jaw-opening exercise was begun. On postoperative day 21, the elastics were placed to assist in guiding protrusion of the mandible anteriorly 24 hours a day. After postoperative day 28, it was possible to completely abandon daytime elastic fixation. The exercise was modified to lateral movement. Case 2 was green-stick condylar fracture, with the IMF with arch bar applied on postoperative day 10. After releasing the IMF, the exercise involved the daily use of several tongue blades, and range of motion increased by wedging additional blades until postoperative day 21. More aggressive stretching was continued with 22 blades on postoperative day 28. On the removal of the arch bar, the occlusion was stable and followed by more aggressive stretching and physical therapy. Both cases were successfully restored and had good results. The authors believe the exercise protocols and algorithms they used may serve as a standard procedure of treatment in condylar fracture caused by angle ostectomy.     

微型钛板在内固定治疗下颌骨粉碎性骨折中的应用:21例临床分析

目的 研究微型钛板内固定术在治疗下颌骨粉碎性骨折中的应用价值。方法 选择2017年3月—2018年2月沈阳市口腔医院收治的下颌骨粉碎性骨折患者21例。所有患者均给予微型钛板坚固内固定,分别在患者下颌骨下缘、上缘、外皮质中部进行固定。观察术后骨折愈合情况及不良反应发生情况。结果 术后3个月内,所有患者均达到骨性愈合,平均时长为（1.53±0.36）个月。21例患者中,6例（28.57%）出现轻微咬合不正,1例（4.76%）发生局部感染,未出现微型钛板断裂、持续疼痛、开口受限、牙损伤、面神经损伤及骨不连患者。结论 微型钛板内固定术适用于无骨缺损的下颌骨粉碎性骨折患者,具有术后骨折愈合良好、时间短、不良反应少的优点。     

张力带单钛板固定结合支抗钉颌间牵引治疗下颌角骨折的临床研究

目的 :探讨联合采用小型钛板张力带固定,外加支抗钉辅助术后颌间牵引治疗下颌角骨折的临床疗效。方法 :下颌角骨折12例患者采用口内切口,单个小型钛板行张力带内固定;同时植入正畸支抗钉,术后行颌间结扎,从术后感染、咬合关系、张口度等方面分析疗效。结果:术后患者伤口均一期愈合,张口度恢复正常,咬合关系良好。仅1例合并糖尿病的患者,术后半年出现伤口裂开、钛板外露现象。结论 :单块小型钛板行张力带固定,辅助支抗钉术后颌间牵引治疗下颌角骨折是一种确实可行的方法。     

Fixation of mandibular angle fractures with a 2.0-mm 3-dimensional curved angle strut plate.

PURPOSE: The aim of this study was to evaluate our experience and complication rate with the use of a 3-dimensional 2.0-mm curved angle strut plate for mandibular angle fracture fixation. PATIENTS AND METHODS: This was a retrospective evaluation of 37 patients with noncomminuted mandibular angle fractures fixated with a transorally placed curved 2.0-mm strut plate. Postoperative intermaxillary fixation was used in 5 patients for a mean period of 22 days. A nonchewing diet was prescribed for 6 weeks. Records were reviewed for demographic information, medical history, fracture characteristics, operative management, and complications. RESULTS: Two patients developed infections requiring plate removal and reapplication of fixation. Both of these patients had a molar in the fracture line that was left in place during the first operation. One patient developed a mucosal wound dehiscence without consequence. After a mean follow-up period of 10 weeks, 39.4% of patients with a postinjury/pretreatment inferior alveolar nerve deficit reported a return to normal sensation. All patients who developed a sensory deficit as a result of surgery reported full recovery of sensation. A persistent sensory deficit appeared to be related to fracture displacement. CONCLUSION: Fixation of noncomminuted mandibular angle fractures with a 2.0-mm curved angle strut plate was predictable. This plate is low in profile, strong yet malleable, facilitating reduction and stabilization at both the superior and inferior borders. Development of a postoperative infection appeared to be related to failure of removal of a molar in the fracture line. The infection rate of 5.4% found in this study compares favorably with that seen with reconstruction plates. Use of this plate did not appear to cause a permanent sensory deficit in this study.     

Mandibular fracture reduction without intraoperative intermaxillary fixation: a technique using two modified reduction forceps

This case report demonstrates a technique that is useful for precompressing mandibular fractures and obtaining anatomical reduction of the fracture edges without the use of peroperative intermaxillary fixation (IMF) in a mandibular fracture by using two modified reduction forceps. The first forcep is positioned at the inferior mandibular border and the other in the neutral zone where it is an ideal location to place a fixation plate in mandibular fractures. This technique is indicated for the anatomic reduction in mandibular fractures of the partial dentate patient.     

钛板对儿童下颌骨生长发育影响的长期随访研究

目的 通过对比下颌骨骨折术后取出和未取出钛板钛钉的患者生长发育情况,探讨钛板钛钉对患者下颌骨生长发育的影响。方法 对行下颌骨手术切开复位坚强内固定术的15例儿童患者进行回顾性研究,根据术后是否取出钛板钛钉分为取钛板组（7例）和未取钛板组（8例）,对患者进行病历收集、术后随访、临床专科检查及影像学测量,比较分析2组患者的容貌形态及影像学资料。结果 15例患者的外形和功能恢复基本满意,未见明显异常,影像学测量表明2组患者左右侧下颌骨长度之差的差异无统计学意义（P>0.05）。结论 钛板钛钉植入对儿童下颌骨的生长发育无明显影响,鉴于二次手术钛板取出可能造成的再次创伤,术后钛板取出术可不常规实施。     

Fixation of mandibular angle fractures: in vitro biomechanical assessments and computer-based studies

Purpose

The purpose of this study was to review the literature regarding the evolution of current thoughts on fixation of mandibular angle fractures (MAFs), based on in vitro biomechanical assessments and computer-based studies.

Methods

An electronic search in PubMed was undertaken in August 2012. The titles and abstracts from these results were read to identify studies within the selection criteria. Eligibility criteria included studies from the last 30 years (from 1983 onwards).

Results

The search strategy initially identified 767 studies. Thirty-one studies were identified without repetition within the selection criteria. Two articles showing significance in the development of treatment techniques was included. Additional hand searching yielded five additional papers. Thus, a total of 38 studies were included.

Conclusions

The osteosynthesis positions as well as the plating technique play important roles in the stability of MAF repair. The only in vitro study evaluating the use of wire osteosynthesis concluded that wires placed through the lower border approach would provide greater stability than those at the upper border. Many studies indicate that the use of two miniplates avoids (or decreases) lateral displacement of the lower mandibular border and opening of the inferior fracture gap. Some studies even suggest that the use of two miniplates may be considered a more “rigid” fixation technique for MAFs than the use of a reconstruction plate. When using two miniplates, the biplanar plate orientation provides greater biomechanical stability than the monoplanar one. However, despite its greater biomechanical stability, the two-miniplate technique has some disadvantages that should also be taken into account. Studies with biodegradable plates suggest the use of at least two plates for each MAF. There are few studies with compression plates, and they have not yet reached a consensus. The solitary lag screw proved to withstand the functional loading of the mandible; however, only few biomechanical assessments were performed. In vitro studies have shown good biomechanical stability with the use of 3-D grid plates. The use of malleable miniplates alone is not sufficient to withstand the early postoperative bite force. Some studies suggest that the segment of the tension band miniplate located at the distal fragment of the MAF should be fixed with three screws. The studies also showed some limitations. None considered the stabilization of the fracture site afforded by the masseter–pterygoid muscle pouch. Most of the studies did not evaluate plating system strength in the long term and therefore did not observe the effect of resorption on the strength of the different biodegradable plating systems. Another limitation of many studies is the absence of a control group. A confounding factor that could not be tested in in vitro investigations is the additional resistance to displacement of jagged fracture margins present in the human fracture.     

Effect of third molars in the line of mandibular angle fractures on postoperative complications: systematic review and meta-analysis

The aim of this systematic review was to verify whether the presence of a lower third molar in the mandibular angle fracture line is associated with postoperative complications. An electronic survey was conducted in five databases. Eligibility criteria included observational and experimental studies that evaluated the association between the presence of the lower third molar in the fracture line of mandibular angle fractures and possible postoperative complications, including infection, paresthesia, necessity of plate removal, temporomandibular joint disorders, malocclusion, dehiscence, and non-union. Thirty-four papers were included in the qualitative analysis and 26 of those in the meta-analysis. The risk of bias of observational studies was assessed by Newcastle–Ottawa scale and of the clinical trials by Cochrane Collaboration risk-of-bias tool. Absence of the third molar was associated with a lower chance of postoperative infection in angle fractures compared to presence of the tooth (odds ratio 0.55, 95% confidence interval 0.34–0.88). No statistically significant difference between the groups was found for the other outcomes evaluated. The findings of this systematic review suggest that the absence of the third molar in the mandibular angle fracture line is associated with a lower postoperative infection rate when compared to angle fractures with a third molar present.